Tow target



Aug.'4, B. E -D'E| MAR 2,898,058

' I TOW TARGET Filed Jan. 20; 1954 Y 5 Sheets-Sheet 1 BRUCE/EDEL MAR;-

INVENT A T TORNEK B. E. DEL MAR Aug. 4; 1959 TOW- TARGET 5 Sheets-Sheet2 Filed Jan. 20, 1954 BRUCliDEL MR9 INVENTOR.

, ATTORNEY.

B. E. DEL MAR TOW TARGET Aug. 4, 1959 5 Sheets-Sheet 5 ItilllllllllllIll Filed Jan. 20, 1954 73 BRUCEfDEL MAR,

INVENTOR.

A TTOkNEK Aug. 4, 1959 B. E. DEL MAR 2,898,058

TOW TARGET I Filed Jan, 20,1954 5 Sheets-Sheet 4 BRUCffDE L MAR IN V ENTOR.

ATTORNEY.

B. E. DEL MAR Aug. 4, 1959 TOW TARGET Filed Ja n.

5 Sheets-Sheet 5 Mm I- Mm f m V a U R 8 ATTORNEK lU itsd States I PatThis invention relates ito an aerial target to be towed by aircraft formilitary training purposes aswell as for carrying out various testsandQexperiments. The inventionis directed toimprovements in such adevice to meet 'lcertain problems relating to towing the aerial'target,tracking the' target with radar, releasing the target fromthe towingaircraft, and lowering the released target by parachute.

' With reference to the towing of the aerial target, a

problem to which the invention pertains is the tendency of the target togain on the towing aircraft'in the course of certain maneuvers of theaircraft, with consequent danger of fouling the .tow cable and possiblehazard to the towing aircraft itself. The invention solves this problemby providingthe tow target with automatic brake means that operates toincrease the air drag whenever the target tends to gain on the leadingaircraft. In this regard, the invention is characterized by the conceptof providing brake means that is responsive to changes in the tension ofthe tow cable and tends to maintain a desirable degree of tension dun'ngflight. One practice of'the invention is further characterized by meansto prevent operation of the brake means'until the targetbecomesair-borne. For this purpose means is provided that is efliective toblock operation of the brake means in response to contact with theground and this ground contacting means releases the brake means foroperation as soon as the tow target rises from the ground atthe'take-oth- The tracking of the target by radar centers on the problemof making the tow target reflect the radar signals to an effectivedegree. The preferred practice'of the' inv'ention not only provides thetowtarget with effective radar reflectors fore and aft, but alsocausesat least o'neof the radar reflectors to rotate continuously in thecourse of the target'flight. A feature of the invention in this respectis-the concept of causing the rotary reflector to wobble or oscillate onits axis. Such oscillation introduces a desirable cyclic variation inthe 7. 2,898,058 Patented Aug. 4,

.2 tow cable to be released fromthe tow target in' response to a radiosignal sent from the towing aircraft. In a secondpractice of theinvention, additional means is provided to release the tow target inresponse to the developmentof excessive slack in the tow cable. If

the radio control fails, 'the towing aircraft may be nianeuvered inamanner to cause excessive slack tofdevelop in the tow cable or the towcable may be released at the towplane end by the "towpilot thus causingau ttr matic release of the tow cable by the target. Thus, the pilot hastwo methods of remote control at his dispjsal to insure release of thecable from the tow target when desired. v i

For those instances in whichthe target is relatively massive, theinventionprovides a control arrangement in which brake means operatesautomatically forincrease in drag to reduce the air speed of the targetas soon as the target is released from the cable and the parachute openssubsequently -only,after the air speed of the target is reduced to apredetermined magnitude. A feature of the invention in this regard isthe concept of using a brake means that responds to reduction of airspeedand in responding determinesthe timing'of the parachute release. v

A further feature of the invention'is the provision of automatic meansto disconnect the parachute completely-when the tow target reachesthegroundw Such provision prevents the parachute from dragging thetarget along the ground in a strong wind with damaging efiect. Theautomatic means is adapted to respond to contact with the ground at theend of a flight, anamcorporates a safeguard against disconnecting theparachute from the tow target in response to contactwith the groundprior to take-off.

\ The various features and advantages of the invention willbe apparentfrom the following'detailed description, considered with theaccompanying drawings.

In the drawings, which are to be regarded as merely illustrative:

Figure 1 is a plan view of a selected embodiment of the invention withportions broken away to reveal'concealed structure; b

Figure 2 is a front elevation of thev device shown in 4 Figure 1;

orientation of the reflecting surfaces which not only makes it easy tolocate the target by radar, but also introduces a signal frequency thatidentifies the target among other detected objects.

Asfor the problem of releasing the target from-ith e' towing'aircraft atthe end of a flight, it is desirable'ffir of all-to provide a reliablearrangement for releasing 1- the tow target fromtthe tow cable and toopen th parachute to lower the target to groundwithout darnage. In onepracticeof the invention, a system ofradio controlis provided whichmakes it possible to cause the embodiment of the invention;

Figure 12 is a view in longitudinal section of a cable- Figure 3 is aside elevation of the same device; I b Figure 4 is a fragmentarylongitudinal section through the same embodiment of the invention; v

Figure 5 is a transversesection taken as indicated by the line 5-5 ofFigure to show the construction of the forward reflector for radarsignals;

Figure 6 is a perspective view of a metal assembly incorporated in theforward reflector;

Figure 7 is a fragmentary plan view on a larger scale of this firstembodiment of the invention with portions broken awayto reveal concealedstructure; 'Figure 8 is a transverse section taken as indicated by theline 8 8 of Figure-7;

. V .Figure 9 is a transverse section taken as indicated by the line 9-9of Figure 7; I Figure 10 is a side elevation of; a brake meansincorporated in the first embodiment ofthe invention;

'4 Figure 11 is a longitudinal sectional *view of a second engagingmeans incorporated in the second embodiment of the invention, thecable-engagingmeans being shown in its normal position;

Figure 13 is a similar view of the cable-engaging means in a secondposition;

Figure 14 is a fragmentary view illustrating a camming action involvedin the operation of the second embodiment of the invention;

Figure 15 is a fragmentary plan view of the portion of the cableengaging means shown in Figure 14; and

Figure 16 is an enlargement of a portion of Figure 11 showingajreleasableconnection for the parachute carriedb the tow target. r 1

' T he invention is applicable to any type of aerial target device thatis adapted to be towed by means of a cable fromf an aircraft and whichis of such character and value 'asf'to'warrant recovery by parachute forre-use. In the first embodiment of the invention that has been selectedbyway of example, the tow target has a hollow "body 'or fuselage,generally designated by numeral 20, which is of triangular configurationin plan and provides adequate aerodynamic surfaces to make'the deviceselfsustaining when drawn through the air at appreciable "velocity bya'tow cable 21.

A The aerial target device has a forward skid 22 for ground contact andhas a pair of rear vertical stabilizers 23, the lower edges of whichcarry additional skids 24 for ground contact. Preferably the target hasa nose member, generally designated by numeral 25, which is constructedto serve as a reflector for radar signals and has a reflector member 26near its trailing edge for the same purpose.

"'Asbest shownin'Figure 6, the nose member 25 includes an integral metalreflector assembly comprising an axial tube 30, a vertical transversedisc 31 on the rear end of the tube and four vanes 32 that are mountedradially on the tube. The disc and the four vanes conform to threeplanes that intersect at the center of the disc, the three planes beingperpendicular to each other." This metal assembly forms four quadrantspaces which are occupied respectively by four bodies 33 of plasticmaterial, the four bodies being shaped to give 'the nose'member agenerally conical configuration.

The'reflector member 26 on the trailing end of the tow target has theconfiguration of threeintersecting discs that are perpendicular to eachother and are concentric to "a common center. This reflector member 26is mounted on a suitable shaft 34 that rotates in a pair of bearings 35;The shaft 34 may be operated in any suitable manner during flight. Inthis instance, the reflector member 26 and the shaft 34 are mounted in astreamlinedlhousing 36 and the shaft 34 carries a rear spinner 37 havingsuitably angled vanes to function as an air screw for rotation .of theshaft in response to the slip stream. Preferably the reflector member 26ismounted on the shaft 34 in a position out of alignment with the shaftaxis so that the reflector member wobbles or oscillates when rotated bythe shaft.

A feature of the first embodiment of the invention is that the towtarget is provided with brake means to increase the drag of the targetwhenever slack tends to develop in the cable 21, the brake means beingresponsive to changes in the tension of the cable. Such an automaticbrake means may comprise, for example, a pair of rectangular members 40that normally lie within the configuration of the fuselage 20, as shownin Figure 8, but are adapted to rotate to positions extending into theair stream, as shown in Figures 2 and 8, for increasing the drag on theflying target. The two rectangular brake members 40 may be mounted ontwo corresponding longitudinal shafts 41 and the fuselage may beprovided with upper slots 42 and lower slots 43 to permit the desiredrotation of the two members. Each of'the two shafts 41 is mounted in apair of bearings 44 and carries a rearward rocker arm 46 (Figure 8), andthese two 4 1 Y arms are interconnected by a coiled spring 48. Thus, thecoiled spring 48 tends to rotate the two shafts in opposite rotarydirections to rotate the two brake members from their normal retractedpositions to their effective positions at which the bottom wall of thefuselage serves as stop means to limit the spring-actuated rotation ofthe two members. Each of the twosh-afts 41 carries a control arm 50 onits forward end as shown in the Figures 4 and 7.

A further feature of this first embodiment of the invention is theprovision of a second brake means effec' tive to decelerate the towtarget as soon as the target is released from the tow cable. This secondbrake means may comprise a forward door-like member 54 (Figure 1) thatis pivotally mounted on the target by an angular rod 55. 1

In addition to these two brake means, the tow target is providedwith aparachute58 that normally lies folded in a rearward parachutecompartment 59 as best' shown in Figure 4, the parachute being connectedto a suitable fitting 60 that is permanently attached insidethecompartment. The parachute 58 is confined in the compartment 59 by apair of doors 61 and 62, that are mounted on suitable hinges 63. As bestshown in Figure 1, the door 62 has a pair of tongues 67 on its swingingedge which overlie the swinging edge of the door'61 fat the closedpositions of the tWO j dQOI'S. Thus, both of the doors 61 and 62 may beheld in closed position by suitable latch means in engagement with thedoor 62. The required latch means may comprise a latch pin 64 that isslidingly mounted in a bushing 65 in engagement with an apertured ear 66(Figures 4 and 9) that extends downward from the door 62. Suitable meansis provided to force the two parachute doors whenever thelatch pin 64 iswithdrawn. For example, as shown in,Figure 9, each of the two doors '61and 62 may be providedwith an operating arm 68 and the two arms may beinterconating the two brake members 40 in response to reducnected by aspring 69 that supplies the door-opening force. V

Any suitable arrangement may be provided for oper.-

tionof tension in the tow cable 21 and any suitable are rangement maybeprovided for releasing the tow target from the cable 21 and forimmediately thereafter operatingthe triangular brake member 54 and, withsuitable time delay, opening the two doors'61 and 62 to release theparachute to open for carrying the tow target to the ground. In thisparticular embodiment of the invention, for example, the cable 21 isyieldingly connected with the tow target for automatic actuation of thetwo brake members 40; a radio-controlled .motor means, is provided toinitiate operation of the triangular brake member 54; and the latch pin64 for releasing the para? chute is made responsive to the operation ofthe triangular brake memberg In the particular construction shown in thedrawings, the cable 21 that tows the target is permanently connected toan elongated fitting 70 which is slidingly received in a suitable sleeve71 that is fixedly mounted in the .pre: viously mentioned axial tube 30of the nose member 25. The slidable cable member 70 is provided with aspline 72 to prevent rotation while permitting free longitudinalmovement. The cable member 70 has a threaded bore-75 at its inner endinto which is threaded a cooperating con: necting member 76. Theconnecting member 76 is connected by aiunivei'sal joint 77 with theshaft 78 of a motor 80 and the motor is suitably mountedfor longitudinalmovement. For this purpose the motor is mounted on a base 81 that isfree to slide longitudinally in a pair of parallel'channel shaped trackmembers 82. The motor 80.is connected by two cables 85 respectively withthe two control arms 50 on the shafts 41 thatcontrol the rectangularbrake members 40, the two: cables being in movable engagement withsuitable guide pulleys 86.

It is apparent that {the described arrangement oper;

:asoaoss atively connects the slidable "cable member 10 at the end.oftthe cable .21vwith the two control arms 50*that nor- .mally :preventthe spring .48 from operating the two rectangular :brake members 40, the,two springs acting to ,pull rearward on the cable member 70 inopposition to ,theforward pull, of the tension in the tow cable. Thuswhen the tow cable is under rsuflicient tension to overcome the spring48, the two rectangularbrake members -'40, are .at their normalretracted positionsentirely inside the configuration of the tow target;but whenever there is ,a tendency for slack to develop in the cable, thespring ,pulls the slidable cable member-7,0 rearward to operate the tworectangular brake members 40,, the brake mem- 'bers rotatingprogressively into the air, stream .to 3pm- ;gr,e ssively;:increasedrag, in a response to, progressivelvre- =du edte sioa n m w; b .e-,.:n-

1 featureofi, this first embodiment :of the invention is -members'40against operation while thetowtarget is on the ground prior ;to'takeofi. ,For this purpose a suitable angular-latch member 88 may bemounted ona pivot pin 89in slot 90 in the forward skid 22. Prior totake-off, the latchmember 88 rests on the ground as shown in Figure 4with the :upwardly extending end .91 of the latch mernber engagingthemotor, base 81 to hold the motor 80 in a forward position in oppositionto the two brake actuating springs 47 and 48. V

The pur'poseof the motor 80 is to unscrew the con-' nect'ing member 76from/the slide member 70 for re- ,lease of ,the :tow' cable .and inaddition to actuate the triangular brake member 54 and to causesubsequent opening or the parachute 58 fI n the present embodiment ofthe invention, it .is' contemplated that the motor will be adapted tooperate the triangular brake member 54 only after the cable .is releasedand then the triangular 'brak'e member will in tum cause theparachute toopen for lowering the tow target tothe ground.

The angular rod 55 that pivotally carries the triangu- 7 lat brakemember .54 has a central offset 94 (Figure 1 ,by -ineans of which it isfixedly connected tothebrake member and one end of .the rod is benttoform an actuating; arm '95. A'suitable coil spring 96 is anchored at oneend, as best shown in Figure 10, and at the other end is' connected tothe actuating'arm 95 to apply a' constant fbrcedending to'move thetriangular brake member 54- about "its" pivot axis to the broken linesinFigure' 10'. p Normallythe triangular brake'member 54 is held in its:down or closedposition .bya'la'tch pin 97 (Figure 4) which is slidinglymounted in a fixed bushing 98 'in engagement with an apertured ear 100that extends downward from the rear edge of the brake member. A cable101; which passes over'a guide pulley 102, is connected at one end tothe latch pin 97 and is connected at the other endto a'reel '103onthemotor shaft 78. There is suflithat normally holds the two'parachutedoors :61 and 62 in closed position. As the triangular brake member 54approaches its upward limit position with decreasing air speed of thetow target, the cable 101 is pulled taut to withdraw the latch pin 64 asshown in broken in Figure 10. Thus completion of the operating movementof the triangular brake member 54 causes the two doors 61 and 62 to flyopen whereupon .the parachute 58 unfolds and opens to lower the releasedtow target to the ground. I p Various arrangements may be employed topermit remote control of the motor 80-from a control station locatedeither onthe towing aircraft or on the ground. In

thisinstance, it is contemplated that the towtarget will carry aradio-responsive control unit, generally designated. by numeral 110,which includes athermionic. tube 111 and also includes ,a relay (notshown) for opening provision of means to latch the two rectangular:brake upright position .shown' in to' completely unscrew the connectingmember 76 from 'the slide member 70 before the cable tightens towithdrawthe latch pin 97. When the latch'pin 97*is'with- 'drawn,*the spring 96acting on theactuating arm 95 "rotatesthe triangular brake member 54upward to 'the upright position shown in broken lines in Figure 10.Since such' rotation of the brake'member 54 is counter to the ainstreamthat envelops the tow target, the triangular brake-member moves upwardslowly to develop progressively increasing drag and does not completeits upward -movement until the air speed of the tow target is reduced toa predetermined degree. Thus, the triangular brake member not onlyserves as brakemeans to increase the drag of the tow target, but alsoserves as sensing means responsive to the air speed of the tow target.

As shown-in Figure 10, a short cable 104 is anchored at one end to ancar 105 on the underside of the'triangular brake member 54'and the otherend of the cable is connected to the previously mentioned latch pin 64and closing the circuit of the motor 80. The tow target carries a numberof batteries 112 which arevs'uitably scattered. for weight distributionand which serve the purpose of energizing the motor and components ofthe radio control unit 110. V The manner in which this first embodimentof the invention serves its purpose will be readily understood from theforegoing description. When the tow target is on the ground .prior totake-oil, the ground-contacting latch member 88 is in position to holdthe motor 80 in a forward position as shown in Figure 4, therebymaintaining the rectangular brake members 40 intheirinoperativehorizontal positions, When the tow target rises from theground, the cable 21 is under sufiicient tension to hold themotor 80slightly forward from the position shown in Figure 4 and the lat-chmember 88 is free to drop OUlI OIf the path of movement of the motor topermit themotor thereafter to move rearward sufficiently for operationof the rectangular brake members 40. v

Whenever the tow target tends to gain on the towing aircraft, thetension of the 'tow cable drops, whereupon the rectangular brake members40 actuated by'the spring 48 respond in a manner to increase the drag ofthe tow target and thereby slow down the target to restore the cabletension. When it comes time to release the tow target from the cable 21at the end of a flight, a radio signal is sent to the radio control unitto cause energizationof the motor 80. The consequent rotation of themotor shaft 78 first results in unscrewing of the connecting member 76from the slidable cable member 70 to free the cable, the cableWithdrawing the slide memberfrom the tow target. Further rotation of themotor shaft-after the cable is released winds in the cable 95 towithdraw the latch pin 97 for release of the triangular brake member 54.The triangular brake member 54 rises slowly against the air stream toreduce the air speed of the target and eventually, when the air speeddrops to a predetermined magnitude, pulls the cable 104 taut to withdrawthe latch pin 64 from the rear 66 .to release the two parachute doors 61and 62. The spring 69 acting on the arms 68 causes the two doors 61 and62 to fly open whereupon thefolded,

parachute 58 is carried out of the parachute compartment by air currentsand opens to lower-the tow target the ground without damage.

The second embodiment of the invention illustratedby Figures 11 to 14 isof the same general character as the first described embodiment and inlike manner carries a motor 120, a radio control unit, and the requiredbatteries (not shown) for energizing the motor and radio control unit.The tow target carries a iolded'parachute 122 in a rear parachutecompartment 123 that is closed by a single door 124. The door 124 ismounted by hinge:

means 125 at its rearward edge to swing upward and rearward for releaseof the parachute 122. A suitable latch."

pin 126 that 'is slidingly mounted in a fixed sleeve 1 27 normallyengages an apertured ear 128tohold the para} chute door 124 in closedposition, the apertured ear extending downward from the dooras shown. VA concealed the air stream, the cable 131 automatically withdraws theretaining pin 130 to permit the parachute to open. The

opened parachute is connected to the-tow target by a forward cable 133and a pair of rearward cables 134.

The target is towed by a suitable tow cable 139 which v is provided witha metalloop 140 at its end for engagement by the tow target in asuitable releasable manner.

An important feature of this second embodiment of the inventionis thatit provides two independent means for release of the cable 139 andopening of the parachute 122 by remote control.

The advantage of such an arrangement is in-the assurance that the towtarget will be released and the parachute will open. If one of theremote control arrangements fails, the other one is available. One

method of remote control is provided by the radio control unit incooperation with the motor 120. The other method of remotecontrolutilizes the tow cable itself, the arrangement being such'that meanscarried by the tow target target is provided with a forwardly extendingmovably mounted member 144, which has a range of at least two positionsand preferably has a range of three positions.

The movably mounted member 144 is normally held in a first position bythe normal tension of the tow cable 139 and is movable from this normalfirst position through a second position to a third position. Themovement of the member 144 from its normal first position to its secondposition results in mechanical release of the metal loop 140 on the endof the tow cable and the further movement from the second position tothe third position, which follows automatically, results in withdrawalof the latch pin 126 for release of the parachute 122. It will bereadily appreciated that the member 144 may be mounted in various waysfor various kinds of movement through the required range of threepositions.

In the construction shown, the member 144 is pivotally mounted by apivot bolt 145 on a suitable bracket member 146, the bracket memberbeing in turn anchored by a pair of bolts 147. The member 144 extendsinto a slot 148 on the forward end of the bracket member 146 near alaterally extending stud 150, as may be seen in Figure 12. It isapparent that since the center of gravity of the member 144 isforward ofthe pivot bolt 145, the member'will tend to drop by gravity from thenormal position the member from its normal position through its secondposition to its third position.

The movably mounted member 144 is formed with a suitable recess on itsforward end to receive the metal loop 140 at the end of the tow cable139 and is formed with a longitudinal slot 156 to house mechanism 140 ofthe tow cable 139 may comprise a hook member I160mounted on a pivot pin161, a bell crank in the formofa generally triangular plate member 162mounted on a pivot pin 163, and a link 164 that interconnects these twomembers, Normally, the triangular member 162 is held against a suitablestop pin 168 by a relatively light spring 169, one end of which isconnected to a pin fixed to member 144 and the other end of which isconnected to the link 164.

1 1 As may be seen in Figure 12, the link 164 is connected to the hookmember by a pivot 170 and is connected to thetriangular' member 162 by asecond pivot 171 and in the normal position of the parts maintained bythe spring 1'69,"the pivot 171 is below center, i.e., is below thestraight line passing through the upper link pivot 17 0 and *the'pivotpin 163 on which the triangular member 162 is mounted. Thus, anytendency for the'hook memberf-160 to release the cable 140 by clockwiserotation 'as' viewed in-Figure 12, will be blocked in a positive mannersince such rotation of the hook member causes the link 164to urge thetriangular member 162 against the stop pin 168. On'the other hand,clockwise rotation of the triangular member 162, as viewed in Figure 12,will rotate the hook member 160 clockwise to the released position shownin dotted lines in Figure 12 and in full lines in Figure 13.

An operating member in the form of a cable 175 is connected at one endto the triangular member 162 by a suitable clevis 176. The operatingcable 175 passes over a small guide pulley 177 on the movable member 144and a pair of spaced guide pulleys 178 inside the tow target. The secondend of the operating cable 175 is connected to the previously mentionedparachute latch pin 126.

Normally the parts of the described mechanism for engaging the tow cableloop 140 are positioned as shown in full lines in Figure 12, with both,the hook member 160 and the triangular member 162 rocked forward andwith the rear end of the link 164 depressed. Whenever slack develops inthe cable 139, the cable will permit the movably mounted member 144 todrop to its second position shown in Figure 13 and, in fact, the cablewill add a downward component of force that will tend to move the member144 to this second position. In addition, the vane 151, in reaction tothe air stream, will provide further force tending to move the member144 downward.

'Since the spring 169 in the mechanism for engaging thetowcable loop 140is a relatively light spring 'and'le'ss tension in the operating cable175 is required to overcome the spring 169 than is required toovercome'the concealed spring 129 associated with the parachute latchpin 126, the downward movement of the member 144'in placing theoperating cable 175 under tension initially causes the hook member 160to release the cable. loop 140. Thus the tow cable 139 may be releasedfrom the tow target by remote control by maneuvering the towing aircraftin such manner as to develop excessive slack in the tow cable. The sameeffect may be achieved also by releasing with the weight of the cablepulling the member 144 downward towards its second position.

Preferably, as shown in Figure 13, when the member 144 drops to itssecond position and thereby actuates the mechanism for releasing the towcable loop 140, the triangular member 162 is moved into abutment with astop surface 179 at the end of the slot 156 so that any further downwardmovement of the member 144 will pull on the operating cable 175 toactuate the parachute latch pin 126 in opposition to the concealedspring 129. Thus, when the member 144 continues to move downward fromits second position by gravity and by pressure of the air stream againstthe vane 151, the member 144 pulls on the ope'rating cable 175 and at athird position of the member 144 lower than the position shown in Figure13, the member 144 retracts the latch pin 126 sufliciently to releasethe parachute door 124. l

Figure 14. It can be seen in Figure 14"that when the movably mountedmember 144 is tilted upward from its normal substantially horizontalposition, the resultant displacement of the pre-flight latch member 180towards the stud 150 causes the cam surface 183 to slide" along the'stoppinwith consequent lifting of theilatch member 180 -"t oa higherangle than its normal angle-relative to the movably mounted member'144.7 1 i As shown in Figure 15, the pivot screw 181 carries a 'spacersleeve 184 and a friction washer 185 that is' made of suitable resilientmaterial such as-rlibber or leather. The pre-fligh't latch member 180 ismounted between the friction washer 185 and a nut 186 on the outer endof the pivot screw 181, the nut 186 being-tightened to providesuflicient pressure'against the latch member to maintain the latchmemberat whatever position it may be placed.

Thus, when the member 144 is tilted upward-tocam the pro-flightlatchmember 18 out of its latching position,

the latch member will remain out of'its latching position until manuallyrestoredafterthe flight.

When the tow target is resting on the ground priorito a flight, thepie-flight latch member l80is in engagement with the stop pin'150 tokeep the movably mountedmemher 144 from dropping downward away-from itsnormal position shown in full lines in Figure l2.- InIthe-course oftake-off, the tow target is initially: drawn forward on the ground orclose to the ground but there is an inevitable upward tugon the towcable 139 by the towing aircraft as the towing aircraft :climbs to liftthe tow target away from the ground. When this upward :tug occurs withthe tow cable 139 extendinglupward-from the towzt'arget at'a substantialangle, the 'movably mounted member .144 is swung upward tothe positionshownlin Figure 14 and .;the consequent camming' action lifts'thelprewflight .latch member 180 to an inoperative position. laThe latchmember 180' remains tilted inthe inoperative position when the movablymounted member144returnstoits normal position as'the tow target levelsolf behind the. towing :aircraft." i

*If desired, suitablespring means such as anelastic cord 187 may beadded to provide aboosting force-to urge the member 144 downw'ardfromits second position to its third position. The elastic cord .187, whichpreferably 'is a Bungee cord, may beconnected at its forward end tothe'previously mentionedstop pin 168 and may be 55 connected at its rearend to one of the screws 214 that anchors the bracket 213;. It can beseen that :theelastic cord creates a relatively small moment fordownward {rotation of the member 144 when the member. 144 is in itsnormal position but creates a substantially larger moment. when themember 144 is in the second position shownin'Figure 13.

The motor 120 that'is controlled by the radio control .unit carriesasuitable angulanoperating am. 188 which in turn carries a pulley 189thatrests against the upper side of the operating cable 175 between thetwo previously mentioned guide pulleys, 178. When the .motor l isenergized by radio control, the operating arm 188'is rotatedcounter-clockwise as viewedinFig-ure 11 to cause :the. pulley 189 on theend of the arm-to cooperate with the two guide pulleys 178 to forma'loop in the operating cable 175, the. pulley 189 moving downwardbetween the two spaced guide pulleys 178. This action places theoperating cable 175 under tension, the first result being 10 release ofthe tow cable 139 and the-subsequent result being actuation of the latchpin 126 to release the parachute door 124 to permit the parachute 122 toopen. 'Thus, the motor 120 ,is capable of operating the hook member 160and the parachute latch pin 126 .even though .the movably mounted member144 remains in its normal position with the tow cable 139 undersubstantial tension.

A further feature of this second embodiment of the invention is theprovision of additional means to cause '10 the parachute 122 to becompletely disconnected from the tow target as soon as the tow target iscarried to the ground by the parachute.- For this purpose the forwardparachute cord 133 is connected to a forward release pin 190 and thereartwo parachute cords 134 areconnected to a pair of'correspondingreleasably secured loops 191.

;Each of the two loops 191 is releasably engaged by a correspondingrelease pin 192 that is mounted in a 'of fixed apertured ears 193. g

The forward release pin 190 of the parachute assembly .20 {is slidinglymounted in a fixed vertical sleeve 196 and, as

best shown in Figure 16, is' recessed at its lower end to form a hook197. Normally, the release pin 190 extends into an aperture 198 in alatch member 199. The latch .member 199 is carried by a downwardlyextending arm .200 that is pivotally mounted on a cross pin 201. The

latch member 199 is connected by a pair of operating cables 202 with thetwo release pins 192 respectively that engage the loops 191 to anchorthe rear cords 134 of the parachute. It is apparent that if the latchmember 199 .31 :is shifted forward from its normal position shown inFig- 11 and 16, the latch member will release the forward r lease pin190 and will pull on the two cables 202 to release the two loops 191.

Normally the latch member 199 is in the position shown .3 Figure 11, butis adapted to be shifted forward autm .matically for release of theparachute in response to contactby the tow target with the ground. Therequired automatic release movement of the latch member199 may beprovided by a forward angular skid 206 that has 4 .a rearward arm 207for contact with the ground and an .upwardly extending arm 208 insidethe tow target for .shifting the latch member 199. The upwardlyextending arm 208 is connected by an operating cable 210 with the arm200 of the latch member 199 so that rocking movement of the'skid 206 bycontact with the ground will pull jthe latch member 199 forward forcomplete disconnection ,of the parachute 122. The angular skid 206extends up- ,ward through a slot 211 on the underside of the tow targetand is mounted by a pivot 212 on a downward extending 'bra'cket 213.'The bracket 213 is anchored inside the ,tow target by suitable screws214.

It is apparent that means should be provided to prevent disconnectionofthe parachute by contact of the skid 206 with the ground prior totake-01f. For this purpose, a .link 215 that extends into a slot 216 in.the skid 206 is j connected by apivot pin 217 to the: skid and isconnected by a pivot pin'218 to .a triangular plate 220 inside the.

tow target. The triangular plate 220 which is rotatablymounted on apivot 2,21 normally rests against a stop bar 222'and is'pivotallyconnected to a rod 223. The rod 223 extends upward through a suitableguide sleeve 224 I and normally abuts against an overhanging forwardportion 225 'of the parachutedoor 124. Thus when the parachute 'door 124is held closed by the latch pin 126, the

rod 223isheld down by the door to cooperate with the stop bar 222 toprevent rotation of the triangular plate 221 and thereby immobilize theskid 206.

It will be noted in Figure 11 that in this locked position ofthe'triangular plate 220, the link 215 is swung downward with the linkpin 218 past center with respect to the line defined by link pin 217 andpivot 221 so that the upward thrust of the skid 196 in response .toground contact is transmitted to the stop bar 222 rather than to the rod223. A suitable spring .226 is provided t'o actuation of the'mechanism,including the.hook,160,for 15 urge the triangular plate 220 clockwise asviewed in center.

Figure 11 whenever the parachute door 124 opens thereby to shift thelink 218 past center in the opposite direction. Thus the spring 226rotates the triangular plate 220 suificiently to retract the link 215past center so that force from the skid through the link will rotate thetriangular plate clockwise away from the-stop bar 222. Y The spring 226is not strong enough-however,

to cause the skid 206 to pull the cable 210 for release of the parachutein the absence of contact by the skid with the ground. a

The manner in which this second embodiment 'of the invention operatesmay be readily understood. Prior to take-off, the skid 206 makes contactwith the ground but isprevented from causing disconnection of theparaengagement with the stud 150 to hold the movably mounted member 144in its normal horizontal position. During take-off, however, themomentary upward tilt of the member 144 by the upward tug of the towcable 139 cams the pre-flight latch member to its upper inoperativeposition.

When it is desired to release the target from the tow cable 139 at theend of a flight, the pilot of the towing aircraft may cause the towcable to be released either by sending a radio signal to the radiocontrol unit or by releasing the tow cable from the towing aircraft orby maneuvering the aircraft to develop substantial slack in the towcable 139. If the motor 120 is energized by the radio control unit, themotor will swing the operating arm 188 downward to cause the operatingcable 175 first to ratate the hook member 160 to release the tow cable139 and second to release the parachute latch pin 126.

Instead of following this procedure to release the tow cable 139, thepilot of the towing aircraft may maneuver to cause substantial slack todevelop in the tow cable or may release the forward end of the tow cablefrom the towing aircraft. In either event the movably mounted member 144will drop from its normal first position to its second position, As themovably mounted member 144 drops to its second position, the operatingcable 175 causes the hook member 160 to release the cable loop 140.Under the force of gravity and the added force provided by the vane 151.in the air stream and the elastic cord 187, the movably mounted member144 continues to drop to its third position and in diong so, pulls onthe operating cable 175 to withdraw the latch pin 126 that holds theparachute door closed.

When the parachute door 124 is released by either of the aboveprocedures, it is opened by the air stream and the parachute 122 isdrawn into the air stream with subsequent withdrawal of the retainingpin 130 to .permit the parachute to open. The openparachute supports thetow target by the forward parachute cord 133 and the two rearwardparachute cords 134. 1 In the meantime, the movement of the parachutedoor 124 'upward to its open position leaves the rod 223 free for upwardmovement and the spring 226 rotates the triangular plate 220sufficiently to shift the link "21S past This action sets the skid 206for operation to completely disconnect the parachute in. response tocontact with the ground.

When the target reaches the ground, the skid 206 is operated by theimpact to pull on the cable 210 and thereby shift the latch member 199forward. The forward shift of the latch member 199 unlatches the forwardrelease pin 190 to disconnect the forward parachute cord 133 from thetarget and at the same time nection of the parachute from the targetprevents the parachute from causing damage by dragging the target alongthe ground on a windy day.

'My. description in specific detail of selected embodiments of theinvention will suggest to those skilled in the art-various changes,substitutions and other departures from my disclosure that properly liewithin the spirit and scope of the appended claims.

' I claim:

1. An aerial tow targetadapted for connection with a cable for towing byan aircraft, said target having: spring means to. resist tension in saidcable; movably mounted means to releasably connect said spring meanswith the cable whereby said connecting means moves in response tochanges in the cable tension; a first brake means on the tow target toincrease the drag thereof, said brake means being responsive tomovements of said connecting means to operate when slack develops in thecable; a. second brake means on the tow target to increase the dragthereof; motor means on said tow target to release said cable means andto cause operation of said second brake means; signal-responsive meansfor energizing said motor means by remote control; and a normally foldedparachute adapted to open in response to said signal responsive means tolower the tow target to the ground.

2. A tow target as set forth in claim 1 which includes means to delayopening of the parachute until the air speed of the tow target isreduced after the cable is released.

3. A tow target as set forth in claim 2 in which said second brake meansis movable in response to reduction in air speed after the cable isreleased; and in which saidparachute is operatively connected with saidsecond brake means to open in response to the reduced air speed.

4. An aerial tow target adapted for connection with a cable for towingby an aircraft, said target having: means forreleasably connecting thetow target to the cable; a normally folded parachute to lower the towtarget to the ground; aerodynamic brake means on said tow target movableagainst the air stream from a normal ineffective positioninto the airstream to decelerate the tow target; spring means to exert actuatingforce on said brake means in the direction to oppose the air stream,

said springmeans being too weak to overcome the resistance of the airstream at high relative velocities of the air stream; means to latchsaid brake means in its normal ineffective position; remotely controlledmeans to release said'connecting means to disconnect the tow target fromthe cable and to release said latch means to permit said spring means toact on said brake means whereby the brake means moves into the airstream in response to reduction in the relative velocity of the airstream; and means to cause the parachute to open in response to themovement of said brake means into the air stream, whereby the parachuteopens when the air speed of the tow target is reduced to a predetermineddegree.

S. A tow target as set forth in claim 4 which includes additional brakemeans on the tow target responsive to the tension of said cable'toincrease the drag of the tow target in response to the development ofslack in the cable.

6. A tow target as set forth in claim 5 which includes means to preventoperation of said additional brake means'in response to contact of thetow target with the ground. 4

7. An aerial tow target adapted for connection with a cable for towingby an aircraft, said target having: connection means for releasablyengaging said cable, said connection means being mounted for movementfrom a normalposition' in engagement with the cable to a second positionand releasing the cable in response to movement to the second position,the direction from said normal position "to said second position being adirection to pull on the cable, wherebythe normal tension in the cable'te nds to maintain said connection means at its normal position; springmeans to move said connection means from said normal position to saidsecond position in the absence of tension-of a predetermined magnitudein the cable thereby -to-cause the connection means to release the cablewhenever the cable-tension drops below said predetermined magnitude, sothat the connection means may be caused to release the cable either byreleasing the leading end of the cable to cause drop in the cabletension or by maneuvering thetowing aircraft to develop slack in the towcable.

8. A tow target as set forth in claim 7 which includes a pre-flightlatch means to hold said connection means in its normal position, saidlatch means being releasable in response to the upward tug of the cableby the aircraft at take-01f.

9. A tow target as set forth in claim 7 in which said connecting meanshas a surface for exposure to the air stream to develop force tending tomove the connecting means to said second position in opposition to thecable tension.

10. A tow target as set forth in claim 7 in which said connecting meansis pivotally mounted to rock forward to its second position in responseto downward pull of the cable created by the development of slack in thecable.

11. A tow target as set forth in claim 10 in which the center of gravityof said connecting means is forward of its pivot axis whereby theconnecting means gravitates to said second position in the absence ofsubstantial tension in said cable.

12. A tow target as set forth in claim 7 which includes remotelycontrolled means on the two target to cause said connection means torelease the cable at either of said positions of the connection means.

13. An aerial tow target adapted for connection with a cable for towingby an aircraft, said target having: connection means for releasablyengaging said icable, said connection means being movable in one respectfrom a normal position through a second position to a third posi tion,said connection means releasing the cable in re sponse to movement fromits normal position to its second position, the direction 'of movementof the connec tion means away from its first position being a directionto pull on the cable, said connection means being biased to move fromits first position to its third position in the absence of substantialtension in the cable whereby the tow target may be released bymaneuvering the towing aircraftto develop slack in the cable; aparachute carried by the tow target to lower the tow target to theground; means 'to retain the parachute in a normal folded state, saidretaining means being releasable in response to movement of saidconnection means to its third position.

, 14. A tow target as set forth in claim 13 which includes means todisconnect said parachute from the tow target in response to contact ofthe tow target with the ground.

15. A tow target as set forth in claim 14 which includes remotelycontrolled means on the tow target to cause said connection means torelease the cable and to cause said parachute to open regardless of theposition of' said connection means.

:16, 'An aerial tow target adapted for connection with a cable fortowing by an aincraft, said target having: means movably mounted on thefront end of the tow target, said means being biased to move from anormal .first position through a second position to a third position; alatch mechanism positioned on said movably mounted means for releasablyengaging said cable,

vsaid movably mounted means being adapted to mainoneendand connected atits-other end to said latch means to release the latch means in responseto movement of said movably mounted means to said second position; and asecond operating means interconnecting said movably mounted means andsaid parachute-releasing means to operate said parachute-releasing meansin response to movement of said movably mounted means to its thirdposition. I

17. A tow target as set forth in claim 16 which includes motor means torelease said latch means and operate said parachute-releasing meansindependently of the movements of said movably mounted means; and whichincludes a signal responsive" means to energize said motor means byremote control. I

18. A tow target as set forth in claim 16 which includes: motor means; athird operating means intencom necting said latch means and said motormeans; a fourth operating means interconnecting said parachute-releasingparachute to open; a first operating means anchored at means and saidmotor means; and means to energize said motor means by remote control toactuate said third and fourth operating means for release of the cableand for opening the parachute.

19. An aerial tow target adapted for connection with a cable for towingby an aircraft, said target having: a rotary radar-reflecting means; andmeans to rotate said rotary means while the tow target is in flight.

20. A tow target as set forth in claim 19 in which said rotary means ismounted for oscillatory rotary motion.

21. A tow target as set forth in claim 19 in which said means to rotatethe rotary means is powered by the air stream adjacent the tow target.

22. An aerial tow target adapted for connection with a cable for towingby an aircraft, said target having: aerodynamic brake means to increasethe aerodynamic drag of the tow target; means responsive to changes inthe tension of the cable to operate said brake means when slack developsin the cable; and means responsive to contact with the ground to preventoperation of said brake means on take-off until the tow target becomesairborne.

23. An aerial tow target adapted for connection with a cable for towingby an aircraft, said target having: means for releasably connecting thetow target to the cable; a normally folded parachute to lower the towtarget to the ground; drag-inducing means to decelerate the tow target;remotely controlled means to release said connecting means and tooperate said drag-inducing means; and means to release said parachute inresponse to deceleration of the tow target to a predetermined degree.

24. A combination as set forth in claim 23 in which said drag-inducingmeans changes in position in response to reduction of the air speed ofthe tow target; and in which said means to release the parachute isresponsive to change in position of said drag-inducing means forautomatic action.

25. An aerial tow target adapted for connection with a cable for towingby an aircraft, said target having: means for releasably connecting thetow target to the cable; radio-responsive means to release saidconnecting means for freeing the tow target from the cable; and meansresponsive to slackening of said cable to release said connecting meansindependently of said radio-responsive means.

26. An aerial tow target adapted for connection with a cable for towingby an aircraft, said target having: a parachute connected to the towtarget to lower the tow target to the ground; releasable means normallypositioned to retain said parachute in compact form inside the towtarget; means to disconnect said parachute from the tow target inresponse to contact of the tow target with the ground; and meansresponsive to said releasable means to prevent operation of saiddisconnecting means prior to the operation of the releasing means.

27. An aerial tow target adapted for connection with a cable for towingby an aircraft, said target having:

15 means for releasably connecting the tow, target to the cable; meansto release said connecting means in response to slack in the cable;means to latch said connecting means against release by slack in thecable prior to take off; and means to release said latch means inresponse to upward tug of the cable at take 011.

References Cited in the file of this patent UNITED STATES PATENTS1,981,461 Miller Nov. 20, 1934 2,111,889 Doepp Mar. 22, 1938 2,124,867Akerman July 26, 1938 7 16 Righter et a1. Sept. 30, 1941 Leslie Mar. 19,1946 1 Fahrney ;Apr. 30, 1946 Griesinger et al. Apr. 29, 1947 BowlesDec. 9, 1947 lessen Feb. 1, 1949 Beirise Aug. 2, 1949 Carlson Sept. 30,1952 Fahrney Aug. 18, 1953 FOREIGN PATENTS Great Britain Apr. 22, 1943

